School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Malaysia.
School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.
Sci Total Environ. 2021 Jul 1;776:145934. doi: 10.1016/j.scitotenv.2021.145934. Epub 2021 Feb 19.
Microbial fuel cells (MFCs) that simultaneously remove organic contaminants and recovering metals provide a potential route for industry to adopt clean technologies. In this work, two goals were set: to study the feasibility of zinc removal from industrial effluents using MFCs and to understand the removal process by using reaction rate models. The removal of Zn in MFC was over 96% for synthetic and industrial samples with initial Zn concentrations less than 2.0 mM after 22 h of operation. However, only 83 and 42% of the zinc recovered from synthetic and industrial samples, respectively, was attached on the cathode surface of the MFCs. The results marked the domination of electroprecipitation rather than the electrodeposition process in the industrial samples. Energy dispersive X-ray (EDX) analysis showed that the recovered compound contained not only Zn but also O, evidence that Zn(OH) could be formed. The removal of Zn in the MFC followed a mechanism where oxygen was reduced to hydroxide before reacting with Zn. Nernst equations and rate law expressions were derived to understand the mechanism and used to estimate the Zn concentration and removal efficiency. The zero-, first- and second-order rate equations successfully fitted the data, predicted the final Zn removal efficiency, and suggested that possible mechanistic reactions occurred in the electrolysis cell (direct reduction), MFC (O reduction), and control (chemisorption) modes. The half-life, t of the Zn removal reaction using synthetic and industrial samples was estimated to be 7.0 and 2.7 h, respectively. The t values of the controls (without the power input from the MFC bioanode) were much slower and were recorded as 21.5 and 7.3 h for synthetic and industrial samples, respectively. The study suggests that MFCs can act as a sustainable and environmentally friendly technology for heavy metal removal without electrical energy input or the addition of chemicals.
微生物燃料电池 (MFC) 可同时去除有机污染物并回收金属，为工业采用清洁技术提供了一种潜在途径。本工作设定了两个目标：研究利用 MFC 从工业废水中去除锌的可行性，并通过反应速率模型了解去除过程。在 22 小时的运行后，对于初始锌浓度小于 2.0 mM 的合成和工业样品，MFC 中锌的去除率超过 96%。然而，从合成和工业样品中回收的锌中，只有 83%和 42%分别附着在 MFC 的阴极表面上。结果表明，在工业样品中，电沉积过程而非电沉淀过程占主导地位。能谱分析 (EDX) 表明，回收的化合物不仅含有锌，还含有氧，这表明可能形成了 Zn(OH)。MFC 中锌的去除遵循一个机制，即在与锌反应之前，氧被还原为氢氧化物。推导出了能斯特方程和速率定律表达式，以了解机制并用于估计锌浓度和去除效率。零级、一级和二级速率方程成功拟合了数据，预测了最终的锌去除效率，并表明可能在电解槽（直接还原）、MFC（O 还原）和控制（化学吸附）模式下发生了机械反应。使用合成和工业样品估算的锌去除反应半衰期 t 分别为 7.0 和 2.7 h。没有 MFC 生物阳极供电的控制样品的 t 值要慢得多，分别为 21.5 和 7.3 h。该研究表明，MFC 可以作为一种可持续的环保技术，用于去除重金属，而无需电能输入或添加化学物质。
